A reverse transcription loop-mediated isothermal amplification (RT-LAMP) method was developed for detection of infectious haematopoietic necrosis virus (IHNV). A set of specific primers were designed based on the IHNV L-protein sequence. IHNV RNA was used as a template for RT-LAMP in a reaction mixture containing reverse transcriptase and Bst DNA polymerase. The RT-LAMP products were observed by the naked eye by adding SYBR Green I fluorescent dye. Positive samples exhibited a fluorescent green color whereas negative samples exhibited a reddish brown color. The RT-LAMP assay had no cross reactivity with infectious pancreatic necrosis virus (IPNV) and viral haemorrhagic septicaemia virus (VHSV). The RT-LAMP assay was highly sensitive, and could detect < 10 pfu IHNV RNA. We confirmed these results using 2% agarose gel electrophoresis. In summary, we developed a sensitive, specific, low cost, and simple RT-LAMP method for rapid field diagnosis of IHNV. The method can achieve high throughput detection, without relying on any special equipment.